Crimpable regenerated cellulose fibers and yarn



Aug. 28, 1962 R. WOODELL 3,050,823

CRIMPABLE REGENERATED CELLULOSE FIBERS AND YARN Filed 001;. 30, 1958INVENTOR RUDLOPH WOODELL ATTORNEY United States Patent 3,050,823 CABLEREGENERATED CELLULGSE FIBERS AND YARN Rudolph Woodell, Kinston, N.C.,assiguor, by mesne assignments, to Beaunit Mills, Incorporated, acorpora- L on of New York Filed ()ct. 30, 1958, Ser. No. 770,761 3Claims. (Cl. 2882) This invention relates to novel and useful crimpablerayon fibers and .a process for their production.

The production of crimpable filaments by extruding two or more viscoseshaving different shrinkage potentials through the same spinneret hole isknown. While these multicomponent filaments are superior in certainrespects to single component filaments, i.e. in ease of crimping andcrimp retention, further improvement in the degree of crimping and crimpreversibility on wetting and drying, particularly in high denier perfilament yarns, is desirable.

It is an object of this invention to provide a new and useful crimpableviscose rayon fiber.

Another object is to provide a czimpable fiber which crimps to a highdegree in water, which has high bulk and improved crimp reversibility.

A further object is to provide a process for producing these fibers.

These and other objects will become apparent in the course of thefollowing specification and claims.-

In accordance with the present invention an integral rayon fiber isprovided having a transverse cross section consisting of twolongitudinal ribbon-like components, disposed side-by-side, a firstcomponent having a heavy, preferably at least 80% skin and a secondcomponent having an elongated narrow shape and a substantially thinnerskin than the first component, one component of the fiber beingwrinkled. Preferably the second component has at least less skin thanthe first component i.e., not over 64% of the cross-sectional area.

The process comprises preparing two viscoses, A and B, adding toin'scose A a small amount of coagulation modifier, extruding the twostreams of viscoses simultaneously in side-by-side relationship throughnarrow, elongated spinneret openings into a coagulating and regeneratingbath containing from about 6.5 to about 10% sulfuric acid, from about 12to about 23% sodium sulfate, and at least about 3% zinc sulfate, viscoseA having a salt index of at least about 5, viscose B having a salt indexof at least about 2, the long axis of the spinneret openings being atleast about 8 to 10 times the length of the short axis, and thereafterstretching the yarn. Preferably, the salt index of viscose A is at leastabout 3 units higher than that of viscose B.

FIGURE 1 is an exploded view of a device useful in the extrusion of theyarn of the present invention.

FIGURE 2 is a rear view of the equalizer and separator section of thedevice illustrated in FIGURE 1.

7 FIGURE 3 is an illustration of the yarn cross section produced asdescribed in Example 1.

Referring particularly to the figures the yarn produced is extrudedthrough the orifices of the spinneret plate 2, the said plate beingpositioned against the equalizer and separator section 3 by means ofinternally threaded spinneret adapter 4, flange S of the spinneret platebeing held against the front face of the equalizer and separator sectionby the face 6 of the said spinneret adapter. Concentric cylindricalseparator rings 7 extend through the equalizer and separator section,the said ringsbeing supported by the pressure equalizer plate 8 (shownin FIG- URE 2) which holds .them in fixed relation to the ciricecumference of the said equalizer and separator section. The concentriccylindrical separator rings are beveled to a sharp edge which extendsbeyond the engaging threads of the equalizer and separator section tosuch an extent that when the spinneret plate 2 is positioned as previously described the sharp edges of the separator rings are immediatelyadjacent to the back face of spinneret plate 2 and so arranged that eachedge bisects each orifice in a particular ring of the said orifices.Pressure equalizer plate 8 (FIGURE 2) contains concentrically arrangedholes 9 fitting into spaces between the concentric separator ringspreviously described and act to control the pressure of, and preventpressure surges in, viscose delivered to the spinneret plate. Pressureequalizer plate 8 fits by threaded means onto a concentric conduit 10which contains openings 11 through which various viscoses may bepressure fed to the system.

The spinneret openings are narrow, elongated slits, preferablyrectangular in shape although the openings may be rounded at the ends ifdesired. The long axes of the spinneret openings are at least about 8 to10 times the length of the short axes and preferably about 16 times thelength of the short axes. It is preferable that the long axis of thespinneret opening be situated radially with respect to the circularspinneret face since this greatly facilitates the extrusion of twoviscoses simultaneously through the opening.

. The following example is cited to illustrate the invention. It is notintended to limit it in any manner.

Example 1 Two viscoses, A and B are prepared in the conventional manner.Viscose A containing 5.0% recoverable cellulose and 6.11% alkali,calculated as sodium hydroxide, is prepared from cotton linters pulpusing 40% carbon disulfide based on the air dry weight of the pulp.Suifrcient sodium N-rnethylcyclohexyldithiocarbamate is added during themixing operation to give a concentration of 0.61% by weight. The viscoseis filtered, deaerated, ripened to a viscosity of 39 poises and a saltindex of 14.4. Viscose B containing 8.60%v recoverable cellulose and5.28% alkali is prepared using 30% carbon disulfide and is filtered,deaerated, and ripened to a Viscosity of 46 poises and a salt index of3.0. Viscoses A and B are then supplied to the spinneret, which hasrectangular shaped openings, by means of separate gear pumps, viscose Abeing supplied at a rate of 48.4 g.p.in. and viscose B at 28.4 g.p.m. sothat substantially equivalent amounts of recoverable cellulose aresupplied by each pump. The viscoses are extruded through a spinneret ofinch diameter having 50 openings of 0.002 inch width and 0.036 inchlength equidistantly spaced in a ring Whose diameter is /s inch. Thelong axes of the spinneret openings are disposed radially with respectto the spinneret face. The two viscoses are extruded through each of thespinneret holes in side-by-side relationship by means of the separatorrings and pressure equalizer assembly previously described.

The viscoses are extruded into a coagulating and regenerating bathcontaining 8.0% sulfuric acid, 17.5% sodium sulfate, 9.5% zinc sulfateand maintained at a temperature of 60 C. The filaments are led for adistance of 20 inches through the bath, then over a Y convergence guideand then for a further distance of inches, the yarn being confined inthe bath by means of a series of roller guides.

The yarn is then led upwardly from the coagulating bath to a firstpower-driven feed wheel, then to a second power-driven feed wheelrotating at the same speed '5 63 as the first but having a suflicientlylarger diameter to stretch the yarn 50%. A hot aqueous solutioncontaining 2.0% sulfuric acid, 3.9% sodium sulfate and 2.1% zinc sulfateat a temperature of 95 C. is jetted onto each of the feed Wheels at thetop. By means of a snubber roller in combination with each feed wheel,the yarn is given a sufficient number of passes around the feed wheelsto give the yarn a travel of 120 inches in this area. The yarn is ledfrom the second feed wheel which has a peripheral speed of 50 y.p.m.downwardly to a centrifugal spinning bucket Where it is wound into acake in the conventional manner. The yarn is purified and dried in theconventional manner. The yarn denier is 1,000.

The yarn filaments are examined by cutting thin transverse crosssections in the conventional manner, dyeing these cross sections andexamining them under high magnification. Cross sections are dyedfollowing the method described by Morehead and Sisson, Textile ResearchJournal, 15, 444- '(1945) except that pontamine yellow dye issubstituted for calcimine yellow dye. Examination of the dyed crosssection shows that one end has a heavy skin while the remainer, as shownin FIGURE 3, is narrow and elongated and has a much thinner skin. Whenthe yarn is placed in water at 90400 C. in a relaxed state followed bydrying in a relaxed state, it is found that the yarn has an excellentspiral type of crimp. Retention of the crimp on repeated wetting anddrying is found to be superior to that of two-component yarns madeoutside the scope of the present invention. Further examination of theyarn filaments at high magnification shows that the filaments arewrinkled or wavy on one component while the other component issubstantially straight. In addition, the yarn is more bulky than otheryarns having the same crimp.

The essential factor in producing the fibers of this invention is theextrusion of two streams of viscoses, one containing a coagulationmodifier and the other containing no modifier, in side-by-siderelationship through elongated spinneret openings to produce filamentshaving narrow, elongated cross sections.

The modified viscose must be spun at a salt index of at least about 5and preferably the index is at least about 10. The unmodified viscosemust be spun at an. index of at least about 2 and is preferably spun atan index in the range of about 2 to about 5 although high indices may beemployed in some cases. If higher indices are employed with theunmodified viscose, then the amount of modifier which is allowed toaccumulate in the spinning bath due to the modifier being leached fromthe spinning filaments must be kept at a very low level in order toobtain the desired filament cross section.

The composition of the viscoses used in the process of this invention isnot critical. Viscoses produced with from about 27 to about 43% carbondisulfide based on the dry weight of the pulp are satisfactory.Preferably the modified viscose is produced with at least about 35%carbon disulfide. The viscose may contain from about 5.5 to about 9.5%recoverable cellulose and from about 4 to about 8% alkali.

Coagul-ating and regenerating baths suitable for use 1 in the presentinvention contain from about 6.5 to about 10% sulfuric acid, from about12 to about 23% sodium sulfate, and at least about 3% zinc sulfate inaddition to the coagulation modifier. Other metal salts which maysupplement the action of the zinc sulfate may be added if desired. Theacidity of the bath should be regulated to aslow a level as iscommensurate with satisfactory spinning.

Addition of a coagulation modifier to the viscose is necessary in orderto produce the desired filament structure.

A group of preferred coagulation modifiers which are suitable for use inthe process of this invention are as follows:

(A) Quaternary ammonium compounds of the formula X", wherein the Rs areorganic groups which contain no more than four aliphatic carbon atoms,at least three of the said groups containing only aliphatic carbon atomsand the fourth of the said groups containing no more than one phenylradical, and where X- is an anion having substantially no surfaceactivity; The use of these compounds is disclosed in United StatesPatent 2,536,014.

Suitable compounds in this group which may be mentioned arebenzyltrimethylammonium hydroxide, tetraethylammonium hydroxide,te'tramethylarnmonium.chloride, phenyltrimethylammonium hydroxide,tetraethanolammonium' hydroxide, tetraethylammonium bromide,tetramethylammonium iodide, tetrapropylammonium hydroxide,tetrabutylammonium chloride, tributylpropylammonium hydroxide,tri(beta-hydroxyethyl)methylammonium hydroxide,tributyl(beta-hydroxyethyl)ammonium iodide, etc. The preferred agents ofthis class are those in which. all four organic groups attached to thenitrogen atom are hydrobon.

(B) Aliphtic monoamines having at least four carbon atoms but containingno radical of more than six carbon atoms. The use of these compounds isdisclosed in United States Patent 2,535,044. Suitable compounds in thisgroup which may be mentioned are triethanolamine, triethylamine,diethanolamine, butylmonoethanolamine, diethylaminoethanol, n-amylamine,diethylamine, dipropylamine, n-butylamine, ethyldiethanol amine,dipropanolamine, propylpropanolamine, hexanolamine, amyldiethanolamine,butylmethylethanolamine, propylethanolamine, cyclohexylethanolamine,N-methylcyclohexylamine, hexamethyleneimine, piperidine,hexyldiethanolamine, etc. The preferred modifiers of this group arethose in which the amino nitrogen is attached to hydrocarbon groups,preferably alkyl groups, and/ or to hydroxyalkyl groups.

(C) Aliphatic diamines containing two amino nitrogen atoms separatedonly by carbon atoms and containing a total of at least three carbonatoms, said diamines having the amino groups attached to aliphaticcarbon atoms, any

monovalent substituent on the amino nitrogens beingalkyl groups of 1 to6 carbon atoms. The use of'these compounds is disclosed in BritishPatent 762,772. Among the aliphatic diamines may be mentioned thefollowing: hexamethylenediamine, tetramethylenediamine,N-methyltrimethylenediamine, N,N'-dimethylethylenediamine, N,N-diisobutylhexamethylenediamine, N,N'-dimethyltrimethylenediamine,4,4-dimethylhexamethylenediamine, N,N'-di-.

ethyl-1,4-cyclohexanediamine, 3-ethoxyethoxyhexamethylenediamine,pentamethylenediamine, octamethylenediamine,N-cyclohexyltetramethylenediamine, N,N'-diallylhexamethylenediamine,N-methylnonamethylenediamine, N-hexyltrimethylenediamine,N,N-dimethylpiperazine, N- butylhexamethylenediamine, etc. The preferredagents of this class are the wholly aliphatic, including cycloaliphatie,diamines which contain only carbon and hydrogen besides the two aminonitrogens and which have a total number of carbon atoms between 4 and14, inclusive, in addition to fulfilling the other requirements statedabove. Still more preferred are the polymethylenediamines of 4 to 14total carbon atoms having from 4 to 8 methylene groups between the aminogroups, and their N-alkyl substituted aesasee derivatives where theN-alkyl groups have from 1 to 4 carbon atoms inclusive.

(D) The salts of N-substituted dithiocarbarnic acids. The use of thesecompounds is disclosed in United States Patent 2,696,423. Among thesalts of N-substituted dithiocarbamic acids may be mentioned, sodiumamyl dithiocarbamate, sodium butyl monoethanol dithiocarbamate, sodiumhexamethylene bis(dithiocarbamate), potassium pentamethylenedithiocarbamate, sodium methyl dithiocarbamate, sodium benzyldithiocarbamate, sodium ethylene bis(dithiocarbamate), sodium1,3-cyclohexane bis(dithiocarbamate), sodium dibutyl dithiocarbamate,sodium dimethyl dithiocarbamate, sodium dioctyl dithiocarbamate, sodiumlauryl dithiocarbamate, sodium cyclohexyldithiocarbamate, lithiumcyclohexyl dithiocarbamate, sodium N-methylcyclohexyldithiocarbamate,the sodium dithiocarbarnates of a mixture of hexadecylamine, 10%octadecylarnine, 25% octadecenylamine and 45% octadecadienylamine,sodium hexamethylene bis(methyl dithiocarbamate), sodium ethylenebis(methyl dithiocarbamate), sodium 1,4-cyclohexane bis(ethyldithiocarbamate), sodium Xylylene bis(dithiocarbarnate), etc. Thepreferred modifiers of this class are the alkali metal salts of monoordiN-substituted dithiocarbamic acids containing no more than 10 carbonatoms in any radical and in Which the nitrogen is attached to aliphaticcarbon.

(E) The ethers of the formula RO-(CH CH O),,R', Where R is alkyl oraryl, n is an integer from 1 to 4 inelusive; and R is hydrogen, alkyl oraryl. The use of these compounds as coagulation modifiers is disclosedin British Patent 741,728. Among the ethers may be mentionedphenoxyethanol, ethoxyethanol, butoxyethanol, methoxyethoxyethanol,butoxyethoxyethanol, phenoxyethoxyethanol, ethoxyethoxyethoxyethanol,butoxyethoxyethoxyethanol, phenoxyethoxyethoxyethanol,butoxyethoxyethoxyethoxyethanol, phenoxyethoxyethoxyethoxyethanol,1-ethenyloxy-2-methoxyethylene, ethylene glycol diethyl ether,triethylene glycol diethyl ether, tetramethylene glycol diethyl ether,triethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.With this class of coagulation modifiers, it has been found that thosecompounds which, in addition to being soluble in viscose, areditficultly soluble in the coagulating bath, i.e., to the extent of lessthan 0.5%, give the best results.

(F) The polyethylene glycols of formula where n is an integer greaterthan 3. The use of these compounds is disclosed in Italian Patent561,552. The polyethylene glycols of formula HO(CH CH O),,H (ethyleneoxide polymers) include all such compounds where n is at least equal to4, i.e., polymers which have a molecular weight of at least 200, andwhich in addition have the required solubility in viscose. Suchcompounds are available commercially in various molecular weight ranges,such as 600, 1500 or 2500. For use as coagulation modifiers, thepolyethylene glycols having molecular weights between about 300 andabout 1000 are preferred. Other coagulation modifiers, as are known inthe art, may also be employed in place of the listed compounds. Varioussuitable ones are described in United States Patents 2,777,775;2,792,278; 2,792,279; 2,792,280 and 2,792,281; British Patents 723,435;730,541; 748,147 and 765,905, and French Patents 1,102,898 and1,111,580.

The yarn should be stretched at least about 40% while passing throughthe bath. Where a hot secondary bath is used, the stretch may beconcentrated in this bath or it may be divided between the two baths asdesired. If a hot secondary bath is not employed, then all of thestretch is imposed on the yarn while passing through the coagulating andregenerating bath by means of tensiontype roller guides.

Preferably the ratio of the yarn draw-01f speed to the linear speed atwhich the viscose is extruded is at least 1.0. This is particularly truewhere the denier per filament is low (-below 8) since under theseconditions the desired elongated shape of the filament cross section maynot be realized if the ratio is too low. Likewise, the ratio should beat least 1.0 if the ratio of length to width of the spinneret opening isbelow about 8.

After the yarn leaves the bath, it is wound into a cake in a centrifugalspinning bucket or wound on a bobbin and thereafter purified and driedin the conventional manner.

After purification, the yarn is preferably given additional stretchafter thorough wetting and is then dried in the stretched condition. Thestretching is conveniently applied by passing the yarn through aslashing machine of the type used in the production of tire cord yarn.If the customary aqueous finish is applied to the yarn, the yarn iswetted with this before stretching.

The yarn crimps readily when allowed to relax in hot water followed bydrying in a relaxed state. Instead of water, various aqueous solutionsas are well known in the art may be used in the crimping operation.

The fibers of this invention may be used wherever rayon fibers arecustomarily employed, however, they are particularly suitable for theproduction of tufted carpets and cut pile fabrics.

Many modifications of the invention described herein will be apparent tothose skilled in the art from a reading of the above without a departurefrom the inventive concept.

What is claimed is:

1. An integral regenerated cellulose rayon fiber having across-sectional width at least 8 times the general thickness, said fiberconsisting essentially of two longitudinal ribbon-like componentsdisposed side-by-side, one of said components having a thick skin whichconstitutes at least of the cross-sectional area, the other of saidcomponents having a thinner skin which constitutes not over 64% of thecross-sectional area, said components having different shrinkagepotentials, one of said components being wrinkled.

2. A crimpable spun yarn composed of fibers as defined in claim 1, saidyarn having the capacity to spontaneously assume a spiral type of crimpwhen placed in water at -100 C. in a relaxed state followed by drying ina relaxed state.

3. An integral regenerated cellulose rayon fiber as defined in claim 1wherein said longitudinal ribbon-like components contain substantiallyequal amounts of regenerated cellulose.

References Cited in the file of this patent FOREIGN PATENTS GreatBritain Nov. 14, 1939 Switzerland July 1, 1935

1. AN INTEGRAL REGENERATED CELLULOSE RAYON FIBER HAVING ACROSS-SECTIONAL WIDTH AT LEAST 8 TIMES THE GENERAL THICKNESS, SAID FIBERCONSISTING ESSENTIALLY OF TWO LONGITUDINAL RIBBON-LIKE COMPONENTSDISPOSED SIDE-BY-SIDE, ONE OF SAID COMPONENTS HAVING A THICK SKIN WHICHCONSTITUTES NOT OVER 80% OF THE CROSS-SECTIONAL AREA, THE OTHER OF SAIDCOMPONENTS HAVING A THINNER SKIN WHICH CONSTITUTES NOT OVER 64% OF THECROSS-SECTIONAL AREA, SAID COMPONENTS HAVING DIFFERENT SHRINKAGEPOTENTIALS, ONE OF SAID COMPONENTS BEING WRINKLED.